Complex plasma is a special and new state of soft matter allowing the investigation of phenomena in classical condensed matter physics, like solidification or melting, defect motion, phase separation, liquid motion, etc., on the individual particle level. The particles, micronsized particles, embedded and charged in surrounding plasma consisting of electrons and ions can be regarded as proxy atoms which form the liquid or solid. Due to the high charge the distance of neighboring microparticles is large, typically a factor 100 larger than their diameter; thus the particles form a strongly coupled Coulomb system. The microparticles' high charge and the slowing down of the dynamics due to their high mass allow the observation of phenomena in real time and real space.
The high mass of the microparticles has also a negative effect, it leads to their sedimentation. This makes microgravity experiments necessary and mandatary to explore the broad phase space of complex plasmas to investigate plasma specific and generic phenomena. With our current lab on the ISS, the PK-4 facility installed in the Columbus Module, and with regular parabolic flights with the next lab for space Ekoplasma, we are fulfilling this task. Complementary, we are performing ground based lab experiments and theoretical and numerical modelling as well as data analysis using newest techniques.
Therefore, complex plasma is a very interdisciplinary research field covering plasma physics, solid and liquid state physics, soft matter and statistical physics, as well as complex systems.
Complex plasma research at the institute currently focuses on: